Modeling of 1-D Unsteady Flows in I.C. Engine Pipe Systems: Numerical Methods and Transport of Chemical Species

The paper describes recent advances in the research work concerning the 1-d fluid dynamic modeling of unsteady flows in i.c. engine pipe systems. A comprehensive simulation model has been developed, which is based on different numerical techniques for the solution of the fundamental conservation equations. Classical (MacCormack method plus TVD algorithm) and innovative (the CE-SE method, the discontinuous Galerkin FEM) shock-capturing schemes have been compared, considering the shock-tube problem and the shock-turbulence interaction problem. Moreover, the tracking of the chemical species along the intake and exhaust duct systems has been investigated, introducing the species continuity equations in the numerical model. The engine test case reported in the paper points out the predicted transport of chemical species in the ducts. In particular, the back-flow of combustion products in the intake pipe and the through-flow of air in the exhaust duct during the valve overlap have been simulated.